I haven't read the novels, and the wiki has no lenses to speak of, so it's a general assumption that the bolts of plasma fire from the energy generator on the front of the weapon...
but I'm not 100% sure, to be honest

well in the novels the lenses were on the ships, and it was alluded that the technology was consistent. But then there was a notice that said the novels' information may or may not be considered canon at any given time, so what I'm saying may no longer be relevant.